A bucket thumb is generally understood in the industry as an implement, which is mounted on an underside of a stick on an excavator boom. The thumb generally opposes the excavator bucket for grasping material held between the bucket and the thumb. There are two main types of bucket thumbs, stiff link thumbs and hydraulically actuated thumbs. Stiff link thumbs are fixed or rigidly orientated relative to the stick and/or the bucket. Conversely, hydraulically actuated thumbs pivot or otherwise move relative to the stick and/or the bucket using a hydraulic cylinder actuated by hydraulic force. In use, the bucket is rotated relative to the stick to grasp and hold material between the bucket and the thumb.
Stiff link thumbs may be connected to the stick with a strut, the position of which can be adjusted to permit adjustment of the angle of the thumb relative to the stick. The strut may include a rigid link detachably securable, using one or more pins, to one of a number attachment points provided on the stick. For example, excavator thumb assemblies typically lock the thumb into a working position with one or more pins frictionally received through one or more holes on the link and one or more corresponding holes on the bracket or attachment point on the stick. Proper alignment of these holes on the link, the bracket, and the attachment point is difficult because thumb assemblies and links can exceed several hundred of pounds.
U.S. Pat. No. 6,203,267 discloses a thumb assembly with a rigid strut connected to a bracket by a pin. The strut includes a T-shaped end that is received in a complementary slot in the bracket. While the T-shaped end and the slot will support the weight of the strut and thumb when the pin is removed to aid in connecting the strut to the bracket, the thumb assembly disclosed in the '267 patent adds significant complexity and cost to the thumb design. Additionally, the thumb assembly disclosed in the '267 patent does not provide a visual indication when the holes in the strut and bracket are sufficiently aligned to insert the connecting pins. Thus, the machine operator must have an additional person located near the bucket or exit the operator station to determine when the holes are sufficiently aligned to insert the connecting pins. This adds time, difficulty, and cost to connecting and adjusting the thumb assembly.
The present disclosure provides a bucket thumb assembly that is directed to overcoming one or more of the problems discussed above.